Developmental disabilities affect 1 in 6 kids

One in every six American children now has a developmental disability, a 15 percent increase since 1997, the Centers for Disease Control and Prevention reported Monday.

The increase is due almost entirely to a rise in the prevalence of attention deficit hyperactivity disorder and is based on reports by parents during a telephone survey, researchers reported in the journal Pediatrics.

But because ADHD has become a catchall phrase for a variety of behavioral problems in schools and elsewhere, it isn't clear whether the increase represents a real upsurge in such developmental delays or simply parents and physicians attributing old behaviors to a disorder that might be treated with drugs.

The data came from the 1997-2008 National Health Interview Surveys, annual telephone surveys in which interviewers question a representative sample of households about health issues. Parents were asked whether their 3- to 17-year-old children had been diagnosed with ADHD, intellectual disability, cerebral palsy, autism, seizures, stuttering or stammering, moderate to profound hearing loss, blindness, learning disorders or other developmental delays of any sort.

In 1997-99, 12.84 percent of children were reported to have such a disability. By 2006-08, that proportion had increased to 15.04 percent, an increase of 1.8 million that brought the total number of affected kids to nearly 10 million. The bulk of that increase was accounted for by ADHD, up from 5.7 percent to 7.6 percent. The rate of autism also showed a significant increase, up from 0.19 percent to 0.74 percent. Profound hearing loss declined slightly, but the rate of most other problems remained constant. The category "other developmental delays," however, showed an increase to 4.24 percent from 3.4 percent.

Experts said physicians may now be more likely to diagnose ADHD for children who, in the past, might have been dismissed simply as slow or unruly. That diagnosis allows children to be treated with such drugs as Ritalin, which can reduce classroom misbehavior but also can make children less responsive.

Some of the increase, however, may be due to better medical technology. Parents are increasingly getting assistance to have children at older ages, which may increase the risk of problems; and more children are being born through assisted-reproduction technology, which also involves risks. Better technology also is increasing the survival of children born prematurely, who have a much higher risk of having developmental problems.